Carburetor



Patented June 21, 1938 PATENT; OFFlCli 2,120,970 cAnBURE'roR.

James G. Allen, Detroit, Mich., assignor to Bendix Products Corporation, South Bend, Ind., a corporation of Indiana Application April 20,

6 Claims.

This invention relates to carburetors, and more particularly to a novel priming device adapted for use in conjunction with the choke valve of a carburetor, to supply a suitable charge of combustible mixture for starting the engine to which the carburetor is attached.

One important object of thisinvention is to provide a device wherein the choke valve may be positively closed, while a suitable charge of combustible mixture is furnished" to the carburetor -in accordance with suction existing in the carburetor to start and warm up the engine.

Another object of this invention is to provide a carburetor with a venturi communicating with i the atmosphere at all times and operable to supply. a rich charge of combustible mixture when the choke valve is closed A still further object of the invention is to provide a novel priming device adapted to withdraw liquid fuel fromthe fuel reservoir through a vented tube communicating with the most restricted section of a priming venturi communicating with the atmosphere and adapted to supply a rich fuel mixture to the engine when the choke valve is in the closed position.

Another object of this invention is to provide a priming venturi adapted to supply a combustible mixture to the carburetor when the choke valve is closed, but so designed and positioned as to 9 become inoperative when the choke valve is opened to such a position as to subject the inner end of the venturi to substantially atmospheric pressure.

Other objects and advantages of this invention 5 will be apparent from the following detailed de-' scription thereof together with the accompanying drawing, submitted for purposes of illustration only, and not intended to define the scope of the invention, reference being had for that purpose 9 to the subjoined claims.

The drawing shows a carburetor having a vertical upper body section II), and a lower body section l2. The lower body section l2 comprises 5 a fuel reservoir [4 equipped with a fuel level .regulating float l6, and a'substantially horizontal air inlet passage l8. A choke shaft 20, rotatably mounted in the walls of the air inlet passage l8 is -provided with a choke valve 22 adapted to be actuated either manually or automatically to variably'control the amount of air admitted to an induction passage 24 formed in the lower body section II and the upper body section In.

The upper body section is provided witha i5 manually controlled throttle valve 26 fixed to a 1935, Serial No. 17,434

throttle shaft 28 rotatably mounted in the walls of the upper body section l0.

Liquid fuel is supplied from the fuel reservoir l4 through the passages 30 and 32 communicating with the main fuel discharge nozzle 34 positioned to discharge into the induction passage 24 at the most restricted section of a'venturi 3'6,

carried by the upper body section I0, and extending into the lower body section l2.

Fuel for idling purposes is provided through the passageway 38 communicating with the main fuel discharge nozzle 34 and extending to the passages 40 and 42 communicating with the induction passage 24 on either side of the throttle valve 2'6,when in the closed position. The quantity of fuel suppliedfor idling purposes is adjustably controlled by means of -a manually operable valve member 44 provided with a spring 46 to prevent accidental rotation thereof.

A combustible mixture formed by the admixture of air admitted through the air inlet passage l8 beyond the choke valve 22 with fuel drawn from the main fuel discharge nozzle 34 is supplied to the induction passage 24 and is passed to the engine beyond the throttle valve 26 under the pumping action of the engine to which the carburetor is attached.

A priming venturi 48 is threaded or otherwise secured in the lower portion of the induction passage 24. Duct 50 extending into the fuel reservoir l4 communicates with the priming venturi 48 at the most restricted section (52) thereof The duct 50 is provided with a vent 54 at the upperextremity thereof, adapted to vent the duct to avoid a syphoning action. The venturi 48 communicates with atmosphere at all times and projects into the inductionpassage at a suitable angle to provide an unobstructed passage of air admitted through the venturi, and fuel drawn through the duct 50, to the upperend of the induction pas- Sega, upon slight opening of the throttle valve '26. The upper end 56 of the venturi 4.8 is beveled, as shown, to be subject to the velocity pressure of the air entering through air inlet l8, so as to equalize the pressures at both ends of the venturi when the choke valve 22 is open and the engine to which the carburetor is attached is being operated at high speed. This arrangement prevents the withdrawal of fuel from the fuel reservoir l4 through the duct 50 at all times except when the choke valve 22 is in the substantially closed position.

The operation of this device is as follows. When it is desired to start the engine, the choke valve 22 is moved to the closed position, whereupon the tion and .air will be drawn through the priming venturi 48 As air flows through this venturi a high suction is exerted at the restricted section 52, whereupon fuel is drawn from the fuel reservoir I4 through the duct 50 to mix with the air passing through the venturi, to provide a rich mixture to start the engine. [When the engine has started, the choke valve 22 is moved toward the open position, admitting an increasing flow of air through the air inlet passage Hi, to destroy the suction exerted in the induction passage 24, thereby decreasing the flow of air through the priming venturi 48, whereupon the flow of fuel through the duct 50 will be decreased. As the choke valve is moved further in theopening direction the pressure within the lower section of the induction passage 24 will approach atmospheric, whereupon the pressures at the inner end 56 of the venturi 48 and at the outer end thereof will be substantially equalized, and' the flow of fuel through the duct 50 will be interrupted. The vent 54, positioned in the duct 50 is operable to prevent fuel from syphoning through the duct 50.

While the irrvention has been described with reference to a preferred embodiment, it is not intended that the invention should be limited to the features shown nor otherwise than by the terms of the following claims.

I claim:

1. A carburetor having an induction passage, choke and throttle valves controlling the induction passage, a fuel reservoir, a fuel nozzle communicating with the fuel reservoir and adapted to discharge fuel into induction passage between the choke and throttle valves, idling fuel passages adapted to supply-fuel to the induction passage posterior to the throttle when the throttle valve is closed, a priming venturi interconnecting the induction passage intermediate the choke and-throttle valves with the atmosphere,

means including a duct positioned at the most restricted section of the priming venturi to supply fuel thereto from the fuel reservoir when the choke valve is closed and the throttle valve is moved from the closed position, and a vent in the duct above the fuel level in the fuel reservoir,

to prevent fuel from flowing through the duct induction passage.

except in the presence of strong suction in the 2. An updraft carburetor having a vertically disposed induction passage,ahorizontally disposed air inlet passage, a choke valve controlling the admission of air to the air inlet passage, a venturi positioned in the induction passage, a fuel reservoir, a fuel discharge nozzle communicating with the fuel reservoir and adapted-4:0 discharge into the induction passage at the most restricted section of the venturi, athrottle valve adapted to control the flow of combustible mixture through the induction passage, means including a priming venturi communicatingwith the atmosphere and dischargin into the induction passage between the cho e valve and its fuel nozzle, means including a duct.to supply the priming venturi with fuel from the fuel reservoir, a vent in the .duct to prevent the flow of fuel to the priming venturi in the absence of high suction in the inductiompassage, said priming venturi being positioned in the induction passage at an appropriate angle to permit an unobstructed flow of combustible mixture hrough the induction pas: sage when the thrott valve is moved from the closed position, and a fuel sump in the induction passage between the choke valve and the fuel nozzle adapted to collect excess fuel. a

3. A carburetor having an induction passage, a choke valve controlling the admission of air to the induction passage, a venturi positioned in the induction passage, a fuel reservoir, a fuel discharge nozzle communicating with the fuel reservoir and adapted to discharge at the most restricted section of the venturi, a throttle valve adapted to control the flow of combustible mixture through the induction passage, means including a priming venturi communicating between the atmosphere and the induction passage, and means to supply the priming venturi with fuel from the fuel reservoir, the upper end of said priming venturi being beveled adjacent the choke valve to subject the priming venturi to atmospheric pressure upon slight opening movement of the choke valve to interrupt the flow of fluid therethrough.

4.111 a carburetor, an induction passage, a throttle and a choke valve controlling the same, a constant level fuel chamber, and priming means including a restricted air inlet of venturi form discharging into the induction passage between the choke valve and the throttle, and a vented fuel .duct extending from the fuel space in the fuel chamber to a point above the fuel level and discharging into the venturi at a point below the fuel level.

5. A carburetor having an induction passage,

choke and throttle valves controlling the induction passage, a fuel reservoir, a fuel nozzle communicating with the fuel reservoir and adapted to discharge fuel into the induction passage between the choke and throttle valves, 2, generally,

opened.

6. In a carburetor, an induction passage having a venturi therein, a throttle and a choke valve controlling said passage, a constant level fuel chamber, a main fuel nozzle connecting the fuel chamber and the venturi, and priming means including a restricted air inlet .into the induction passage between the choke valve and the venturi, said airinlet being of venturi shape, and a fuel duct extending from the fuel space in the fuel chamber to a point above the level thereof and discharging in said air inlet,' said fuel duct being provided with a vent above said fuel level.-

- J'AMES G. ALLEN. 

